Method and system to extend connection time of a talkgroup conversation based on historical talkgroup statistics

ABSTRACT

A method for extending the connection time of talkgroup radios in a talkgroup conversation based on historical talkgroup statistics is provided. A talkgroup conversation request intended for a talkgroup is received from a first mobile unit. A group call grant message is sent to radios that are members of the talkgroup. The group call grant message initiates the talkgroup conversation with a first talkgroup call and includes an extended connection time value. Once it is determined that the first talkgroup call has ended, all radios that are members of the talkgroup are kept in a connected state. An extended connection timer utilizing the extended connection time value is started. Upon expiration of the extended connection timer, all radios that are members of the talkgroup are set to an idle state.

BACKGROUND OF THE INVENTION

In Land Mobile Radio (LMR) communication systems, a mobile devicemonitors a control channel, for example for group call activity, such astalkgroup calls. For radios that have fallen back to Long Term Evolution(LTE) systems, a mobile radio goes to idle state after ten seconds ofinactivity.

If a new talkgroup call is started, an idle mobile radio that is on theLTE system and in the talkgroup needs to be paged and switched from idlemode to connected mode. In current systems, the paging cycle is 1.28seconds. If the initial page fails, a nationwide page is required toattempt to locate the mobile radio. This adds additional time, perhapsup to several seconds, until the radio is in connected mode and part ofthe call. To avoid audio truncation of the start of the audio of thetalkgroup call, the audio is typically not sent until all talkgroupradios are in connected mode. Such a delay is unacceptable for missionscritical use cases.

Therefore, a need exists for a method and system to begin talkgroupcalls immediately without having audio truncation. Further, a needexists to start talkgroup calls immediately with audio truncation andwithout draining the batteries of mobile devices that are part of thetalkgroup.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, which together with the detailed description below areincorporated in and form part of the specification and serve to furtherillustrate various embodiments of concepts that include the claimedinvention, and to explain various principles and advantages of thoseembodiments.

FIG. 1 depicts a system diagram of a communication system in accordancewith an exemplary embodiment of the present invention.

FIG. 2 depicts a PTT Server in accordance with an exemplary embodimentof the present invention.

FIG. 3 depicts a flowchart in accordance with an exemplary embodiment ofthe present invention.

FIG. 4 depicts a flowchart in accordance with an exemplary embodiment ofthe present invention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

The apparatus and method components have been represented whereappropriate by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present invention so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment provides mission critical talkgroup servicewhile eliminating truncation and delay when some of the member talkgroupradios are on a Broadband LTE (Long Term Evolution) system.

FIG. 1 depicts a system diagram of a communication system 100 inaccordance with an exemplary embodiment of the present invention.Communication system 100 preferably includes a PTT server 102, a landmobile radio (LMR) network 112, a broadband network 114, andcommunication devices 104, 106, 108, and 110. The communication devices104, 108, 108, and 110 are sometimes referred to as subscriber units. Auser 116 of communication device 108 may carry the communication device108, for example, on a belt or within a pants pocket. The user 116 isalso in close proximity to communication device 106 (for example, withinabout twenty (20) feet or less). Communication devices 104, 106, 108,and 110 additionally form talkgroup 120. In this embodiment,communication device 104 is connected to LMR network 112, whilecommunication devices 106, 108 and 110 are connected to broadbandnetwork 114.

PTT server 102, described more particularly below with respect to FIG.2, is also communicatively coupled to LMR Network 112 and BroadbandNetwork 114. User 116 may be in close proximity to multiplecommunication devices, such as communication device 106 and 108, andtherefore may hear audio output from both at the same time. Because ofthis, communication devices 106 and 108 may cause an echo if theirrespective audio transmissions are unsynchronized, and thereforecommunication system 100 is set up to synchronize audio transmissionsbetween devices with different speeds and different networks to reduceechoes.

FIG. 1 illustrates a graphical representation of an example talkgroup120 that includes communication devices 106, 108, and 110. Although eachcommunication device 106, 108, and 110 is shown affiliated withtalkgroup 120, devices 106, 108, and 110 may be associated with one ormore other talkgroups. In addition, throughout the followingdescription, reference is made to talkgroup 120 and communicationdevices 106, 108, and 110 to provide examples of the methods and systemsbeing explained. Talkgroup 120 is merely exemplary and has beensimplified for the sake of explanation. In some embodiments,communication system 100 includes more or fewer communication devicesand more or fewer talkgroups. In some embodiments, the talkgroups havemore or fewer affiliated communication devices. In some embodiments, thetalkgroups do not have the same number of affiliated communicationdevices. While FIG. 1 illustrates four communication devices 104, 106,108, and 110 for clarity purposes, it should be understood that themethods herein can be used with more or fewer communication devices.

FIG. 2 schematically illustrates PTT server 102 in more detail. In theexample provided, PTT server 102 includes an electronic processor 204, astorage device 206, and a communication interface 208. Electronicprocessor 204, storage device 206, and communication interface 208communicate over one or more communication lines or buses. Wirelessconnections or a combination of wired and wireless connections are alsopossible.

Electronic processor 204 may include a microprocessor,application-specific integrated circuit (ASIC), field-programmable gatearray, or another suitable electronic device. Electronic processor 204obtains and provides information (for example, from storage device 206and/or communication interface 208), and processes the information byexecuting one or more software instructions or modules, capable of beingstored, for example, in a random access memory (“RAM”) area of storagedevice 206 or a read only memory (“ROM”) of storage device 206 oranother non-transitory computer readable medium (not shown). Thesoftware can include firmware, one or more applications, program data,filters, rules, one or more program modules, and other executableinstructions. Electronic processor 204 is configured to retrieve fromstorage device 206 and execute, among other things, software related tothe control processes and methods described herein.

Storage device 206 can include one or more non-transitorycomputer-readable media, and may include a program storage area and adata storage area. The program storage area and the data storage areacan include combinations of different types of memory, as describedherein. In the embodiment illustrated, storage device 206 stores, amongother things, instructions for the processor to carry out the methods ofFIGS. 3 and 4.

Communication interface 208 may include a transceiver (for example, aWi-Fi or Ethernet transceiver) for communicating over one or more wiredor wireless communication networks (for example, the land mobile radio(LMR) network 112 or the broadband network 114) or connections.

In some embodiments, PTT server 102 performs machine learning functions,as described above. Machine learning generally refers to the ability ofa computer program to learn without being explicitly programmed. In someembodiments, a computer program (for example, a learning engine) isconfigured to construct an algorithm based on inputs. Supervisedlearning involves presenting a computer program with example inputs andtheir desired outputs. The computer program is configured to learn ageneral rule that maps the inputs to the outputs from the training datait receives. Example machine learning engines include decision treelearning, association rule learning, artificial neural networks,classifiers, inductive logic programming, support vector machines,clustering, Bayesian networks, reinforcement learning, representationlearning, similarity and metric learning, sparse dictionary learning,and genetic algorithms. Using all of these approaches, a computerprogram can ingest, parse, and understand data, and progressively refinealgorithms for data analytics.

FIG. 3 depicts a flowchart 300 in accordance with an exemplaryembodiment of the present invention. A typical incident involves a burstof radio traffic that could include users on LMR sites and LTE sitesutilizing a Backup PTT solution.

PTT Server 102 receives (301) a talkgroup conversation request. Thecommunication system determines the talkgroup associated with thetalkgroup conversation request, and transmits a group call grant messageto all members of the talkgroup that are currently registered inBroadband Network 114. In accordance with an exemplary embodiment, anextended connection time value is included in the group call grantmessage.

As used herein, a talkgroup conversation means a series of relatedtalkgroup calls. For example, a member of the talkgroup may initiate atalkgroup conversation by pushing a PTT button on a radio. This userwill speak into a microphone on the land mobile radio, and this audio istransmitted to other members of the talkgroup. Upon finishing the audiomessage, the user releases the PTT button and this talkgroup call iscompleted. However, the talkgroup conversation remains open in order togive other members, or the initiating user, the opportunity to transmita talkgroup call within the current conversation. Talkgroupconversations generally include back and forth calls, often followed byan officer taking action. These talkgroup conversations need to occur ina mission-critical fashion with minimal audio truncation or delay.

For the first talkgroup call in a talkgroup conversation, audiotransmission will be held off in order to give enough time forparticipating broadband radios in the talkgroup to wake up and indicateparticipation in the talkgroup call. This avoids audio truncation of thebeginning of the audio for the new talkgroup call. In accordance with anexemplary embodiment, audio holdoff will not be performed for anysubsequent calls within this talkgroup conversation because the radiosin the talkgroup will remain in connected mode rather than switch toidle mode after the first call in the talkgroup conversation ends, whichis what happens in current communication systems.

PTT Server 102 transmits (303) the talkgroup call, which in an exemplaryembodiment is the first talkgroup call in this talkgroup conversation.

At some point, the current caller will release the PTT button andthereby stop sending voice to other members of the talkgroup, at whichpoint this portion of the talkgroup conversation, this talkgroup call,ends (305). In current communication systems, all radios in thetalkgroup call would move from connected mode to idle mode. Inaccordance with an exemplary embodiment, this does not necessarilyhappen.

PTT Server 102 assumes (309) all radios in the current talkgroup are ina connected state. By assuming that the talkgroup radios are in aconnected state, talkgroup call delay is eliminated due to the talkgroupradios not having to go through the sleep, page, and wake up cycles. Inaddition, since the talkgroup radios remain in the connected state,audio truncation does not happen. Further, any new transmission, such asa new talkgroup call, can be started immediately without the need forpaging members of the talkgroup, and therefore there are no audiotruncation issues.

The system starts (311) an extended connection timer. For the first callin this talkgroup conversation, the extended connection time is set tothe value included in the group call grant message. For future talkgroupcalls within this talkgroup conversation, the extended connection timecan be different from the extended connection time included in the groupcall grant message. In a first exemplary embodiment, the extendedconnection time can be adjusted to subtract the elapsed time in thecurrent talkgroup conversation from the extended connection timeincluded in the group call grant message. In this manner, the timer willexpire around the original time set when the talkgroup conversation isstarted and not be continuously reset with each talkgroup call. In asecond exemplary embodiment, the extended connection time can bemodified as new data used to calculate the extended connection time isreceived. For example, talkgroup members can join or leave theconversation, priorities of users can change, roles of talkgroup userscan change, to name a few.

PTT Server 102 determines (313) if the extended connection timer hasexpired. If the extended connection timer has expired, PTT Server 102assumes that all radios in the talkgroup that are connected to BroadbandNetwork 114 have been set to an idle state. Having the talkgroup radiosin idle state extends battery life for the talkgroup radios. The processthen ends (399).

If the system determines that the extended connection timer has notexpired as determined at step 313, the system determines (315) if a newtalkgroup call has been started. If the system determines that a newtalkgroup call has started, which in this embodiment means that a callthat is a part of a talkgroup conversation has started, the processreturns to step 303 to process the talkgroup call at each of thetalkgroup radios. Because all talkgroup radios are in the connectedstate, the talkgroup call can start immediately without waiting forradios to be paged and join the call ad without having to worry aboutaudio truncation.

If the system determines at step 315 that a new talkgroup call has notstarted, the system returns to step 313 determine if the extendedconnection timer has expired.

FIG. 4 depicts a flowchart 305 in accordance with an exemplaryembodiment of the present invention. Flowchart 305 depicts an exemplaryembodiment of a method for calculating an extended connection timeutilizing a closeness attribute for the talkgroup.

PTT Server 102 sets (401) the extended connection time to a defaultvalue. In accordance with an exemplary embodiment, if PTT Server 102determines that a talkgroup's current traffic pattern matches historicaldata that indicates that the talkgroup conversation will last aparticular length of time, the radios in the talkgroup will stayconnected for approximately that length to eliminate audio truncation ontalkgroup calls within a talkgroup conversation. Once this timerexpires, the radios in the talkgroup then go into Idle mode to maintainbattery life.

PTT Server 102 determines (403) a closeness attribute for thistalkgroup. The Closeness Attribute represents the closeness of talkgroupcalls within a cluster, for example how long an overall talkgroupconversation lasts and the probability that another call within thetalkgroup conversation will start prior to the end of the extendedperiod of time. The Closeness Attribute is preferably used as anextended connection time at the end of a talkgroup call to keep allmember talkgroup radios in the connected state for an extended period oftime. A new call arrival within a conversation is highly probable tohappen within the extended connection time, the time in which all themember talkgroup radios are still in their connected state. Eachdistinct talkgroup will have a closeness attribute associated with thatparticular talkgroup.

In accordance with an exemplary embodiment, the traffic pattern of thetalkgroup is continuously analyzed and used to update the closenessattribute. This in turn helps estimate how long a particular talkgroupconversation will last and what period of time after a call end expectsrelatively high probability of a call arrival. PTT Server 102 usesstatistically-learned group behavior to update the closeness attribute.Further, this can also help predict when audio will be present on thetalkgroup. This helps minimize audio truncation, speeds up the start oftalkgroup calls, and helps radios in the talkgroup conserve batterypower by not remaining in the connected state for more time than isnecessary.

The traffic pattern is preferably impacted by various factors. Forexample, the traffic pattern can be impacted by the number of talkgroupmembers, the user role in the call, or the incident type. In addition,the closeness attribute can change over time, for example as differentusers join the talkgroup, the number of users in the talkgroup, and theincident types involved in the talkgroup call. In an exemplaryembodiment, the closeness attribute is continuously learned,categorized, and adjusted by PTT Server 102.

The communication system/PTT Server saves (405) the closeness attributeand the extended connection time. The extended connection time value isincluded in a group call grant message that starts a new talkgroupconversation.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings. The benefits,advantages, solutions to problems, and any element(s) that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as a critical, required, or essential features orelements of any or all the claims. The invention is defined solely bythe appended claims including any amendments made during the pendency ofthis application and all equivalents of those claims as issued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has”,“having,” “includes”, “including,” “contains”, “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element preceded by“comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . .a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially”, “essentially”,“approximately”, “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

It will be appreciated that some embodiments may be comprised of one ormore generic or specialized electronic processors (or “processingdevices”) such as microprocessors, digital signal processors, customizedprocessors and field programmable gate arrays (FPGAs) and unique storedprogram instructions (including both software and firmware) that controlthe one or more processors to implement, in conjunction with certainnon-processor circuits, some, most, or all of the functions of themethod and/or apparatus described herein. Alternatively, some or allfunctions could be implemented by a state machine that has no storedprogram instructions, or in one or more application specific integratedcircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic. Of course, acombination of the two approaches could be used.

Moreover, an embodiment can be implemented as a computer-readablestorage medium having computer readable code stored thereon forprogramming a computer (e.g., comprising an electronic processor) toperform a method as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, a CD-ROM, an optical storage device, a magnetic storagedevice, a ROM (Read Only Memory), a PROM (Programmable Read OnlyMemory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory) and a Flashmemory. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

We claim:
 1. A method comprising: receiving a talkgroup conversationrequest intended for a talkgroup from a first mobile unit; sending agroup call grant message to radios that are members of the talkgroup,the group call grant message initiating the talkgroup conversation witha first talkgroup call and including an extended connection time value;determining that the first talkgroup call has ended; keeping all radiosthat are members of the talkgroup in a connected state; starting anextended connection timer utilizing an adjusted extended connection timevalue; and upon expiration of the extended connection timer, each of theradios that are members of the talkgroup transition to an idle state. 2.The method of claim 1, the method further comprising the step ofstarting a second talkgroup call in the talkgroup conversation withoutpaging the radios that are members of the talkgroup.
 3. The method ofclaim 2, the method further comprising the step of cancelling theextended connection timer.
 4. The method of claim 1, wherein theadjusted extended connection time value comprises the extendedconnection time value minus an elapsed time of the talkgroupconversation.
 5. The method of claim 1, wherein the adjusted extendedconnection time value comprises the extended connection time valueadjusted by at least one of additional radios joining the talkgroup,radios leaving the talkgroup, a priority of one of the radios that aremembers of the talkgroup, and a changed role of one of the radios thatare members of the talkgroup.
 6. The method of claim 1, the methodfurther comprising the step of starting a second talkgroup call in thetalkgroup conversation without performing audio holdoff.
 7. The methodof claim 1, the method further comprising the step of starting a secondtalkgroup call in the talkgroup conversation, wherein the secondtalkgroup call is started immediately.
 8. A Push To Talk (PTT) Servercomprising: a communication interface that performs: receiving atalkgroup conversation request intended for a talkgroup from a firstmobile unit; and sending a group call grant message to radios that aremembers of the talkgroup, the group call grant message initiating thetalkgroup conversation with a first talkgroup call and including anextended connection time value; and a processor that performs:determining that the first talkgroup call has ended; keeping all radiosthat are members of the talkgroup in a connected state; starting anextended connection timer utilizing an adjusted extended connection timevalue; and upon expiration of the extended connection timer, each of theradios that are members of the talkgroup transition to an idle state.